PLEASE PLEASE PLEASE HELP!!!!!!Questions About the Nervous System and the Action Potential…?
Question by Macarius the Great: PLEASE PLEASE PLEASE HELP!!!!!!Questions about the nervous system and the action potential…?
I need to clear up some things for my test tomorrow, so I’ll just tell you my understanding of one of the concepts with questions, so please correct anything you see wrong:
Chillin’ Stage: In any nerve cell, it has a resting potential of -70 mV because of the tendency of more Na+ ions diffusing out of the cell than K+ ions diffusing into the cell (3:2 ratio)….so basically you have more Na+ ions OUTSIDE and K+ ions INSIDE of the cell.
Depolarization: When the nerve cell is stimulated, sodium ion gates open, allowing Na+ ions to rush INSIDE the cell…..so now we have K+ and Na+ inside the cell compared to very few K+ & Na+ ions outside of the cell, raising the net charge relative to the interior to -50 mV.
Repolarization: As the stimulus moves through the axon [((what *exactly* is the “stimulus”? Is it an electric flow of electrons, or a flow of “neurotransmitters” (don’t know what they do)))]…..through the axon, the Na+ gates close and K+ gates open, reversing the charge back to -70 mV, but the Na+ & K+ ions in the wrong place. [((in order for this to happen, the K+ gates must have allowed more K+ ions outside of the cell, is this correct?))] The ions go back to its correct spot by actively transporting through the Na+/K+ gates, bringing it back to the chillin’ stage….what’s this stage exactly called?
NOW: after all this seems lovely….but how does it transmit *along* the axon? Also: how the eff is the stimulus supposed to move through the axon simply by the random exchanging of K+/Na+ in a neuron??????????????????????????????????…
Please help me I wanna do good in this test, also ADD any other details that may be beneficial.
Thx in advanced!!
AH! Resting potential…of course, of course.
Still doesn’t answer the question, “how does it transmit along the axon & how is the stimulus supposed to move through the axon simply by the random exchanging of K+/Na+ in a neuron?”
Best answer:
Answer by Scientist VK
Chillin stage??? I believe it is called a resting potential (variation maybe) but correct anyway
Depolarization:- 3Na+ diffuses into the axon and 2K+ diffuses out of the axon. This leaves the inside of axon more positive than the outside
Repolorisation is the opposite of depolarization. An action potential causes Na+ to be on the wrong side of the axon so the neurone needs to pump the Na+ back outside the axon. During this time K+ channels remain shut. This causes the outside of the axon to reach 80mV. K+ channels open allowing K+ into the axon resulting in a resting potential of -70mV
A stimulus is something that triggers an impulse (action potential-Na moves into the axon). The stimulus needs to be intense enough to trigger an action potential
Neurotransmitters such as acetylcholine/ dopamine etc have different effects but they have nothing to do with depolarization of the neurone. Neurotransmitters are released from the presynaptic neurone when there is an increase in Ca2+ concentration in the neural cytoplasm. They then diffuse across the synaptic cleft and attach to receptors on the post synaptic neurone. This causes depolarization of the neurone (opening of Na+ gates) which causes Na+ to diffuse into the axon causing an action potential
Give your answer to this question below!